Enabled brave search promotion button study for CA/GB in beta/nightly

[simonhong]

Related issue - brave/brave-browser#40776

also removed CA/GB from search promotion banner study.

[github-actions]

✅ Test Seed Generated Successfully

To apply the test seed:

1. Desktop: Launch the browser with --variations-pr=1275.
   Android: Set the command line to --variations-pr=1275 in debug menu, restart the browser.
   iOS: Set Variations PR to 1275 in Brave Core Switches debug menu, restart the browser.
2. Wait 5-10 seconds to fetch the seed.
3. Restart the browser to apply the seed.
4. Ensure Active Variations section at brave://version starts with the expected seed version (see below).

Seed Details

Parameter	Value
Version	pull/1275@783ce3e2f737f54091ef23b0f4abc7e33b6418f1
Uploaded	Wed, 15 Jan 2025 05:37:56 GMT
PR commit	4fe12b9
Base commit	8f14ef7
Merge commit	783ce3e
Serial number	c1f75a4f1febc0456fa7c8667e2584c3

[kjozwiak]

Quick Note: The following basically ensures that the Griffin study is working as expected. The feature was already verified by QA via brave/brave-browser#40776.

Nightly verification:

Test Case #1 - BraveSearchPromotionButtonStudy:Enabled (Using CA - Canada)

Verification PASSED on Win 11 Pro x64 using the following build(s):

Brave | 1.76.19 Chromium: 132.0.6834.83 (Official Build) nightly (64-bit)
-- | --
Revision | e4fe296fa977dbe8f41c46d7c3f43d09b66a5309
OS | Windows 11 Version 24H2 (Build 26100.2605)

• launched 1.76.19 Chromium: 132.0.6834.83 using the following
  • brave.exe --enable-logging=stderr --variations-pr=1275 --variations-override-country=ca

Quick Note: we're using --variations-override-country=ca due to griffin.brave.com not supporting x-country header

• restarted 1.76.19 Chromium: 132.0.6834.83
• ensured pull/1275@783ce3e2f737f54091ef23b0f4abc7e33b6418f1 via brave://version
• ensured that BraveSearchPromotionButtonStudy:Enabled was appearing under brave://version
• change the default SE from Brave -> DDG via brave://settings/search
• ensure that the Brave promotional banner is being displayed via the omnibox when typing a search term

`Example	Example	Example

BETA verification:

Test Case #2 - BraveSearchPromotionButtonStudy:Enabled (Using GB - UK/Great Britian)

Verification PASSED on Win 11 Pro x64 using the following build(s):

Brave | 1.75.161 Chromium: 132.0.6834.83 (Official Build) beta (64-bit)
-- | --
Revision | 7e59e37e24ad33062e0f20e842236aa03f579407
OS | Windows 11 Version 24H2 (Build 26100.2605)

• launched 1.75.161 Chromium: 132.0.6834.83 using the following
  • brave.exe --enable-logging=stderr --variations-pr=1275 --variations-override-country=gb

Quick Note: we're using --variations-override-country=gb due to griffin.brave.com not supporting x-country header

• restarted 1.75.161 Chromium: 132.0.6834.83
• ensured pull/1275@783ce3e2f737f54091ef23b0f4abc7e33b6418f1 via brave://version
• ensured that BraveSearchPromotionButtonStudy:Enabled was appearing under brave://version
• change the default SE from Brave -> DDG via brave://settings/search
• ensure that the Brave promotional banner is being displayed via the omnibox when typing a search term

`Example	Example	Example

Test Case #3 - BraveSearchPromotionButtonStudy NOT meeting country (Using PL - Poland)

• launched 1.75.161 Chromium: 132.0.6834.83 using the following
  • brave.exe --enable-logging=stderr --variations-pr=1275 --variations-override-country=pl

Quick Note: we're using --variations-override-country=pl due to griffin.brave.com not supporting x-country header

• restarted 1.75.161 Chromium: 132.0.6834.83
• ensured pull/1275@783ce3e2f737f54091ef23b0f4abc7e33b6418f1 via brave://version
• ensured that BraveSearchPromotionButtonStudy is NOT appearing/being used under brave://version
  • due to country not being either CA or GB
• change the default SE from Brave -> DDG via brave://settings/search
• ensure that the Brave promotional banner is NOT being displayed via the omnibox when typing a search term

`Example	Example	Example	Example

Release verification:

Test Case #4 - BraveSearchPromotionButtonStudy NOT used (Using CA)

Verification PASSED on Win 11 Pro x64 using the following build(s):

Brave | 1.74.48 Chromium: 132.0.6834.83 (Official Build) (64-bit)
-- | --
Revision | abcdb1e011a32c5baf82019bf0b537c22baeb92d
OS | Windows 11 Version 24H2 (Build 26100.2605)

• launched 1.74.48 Chromium: 132.0.6834.83 using the following
  • brave.exe --enable-logging=stderr --variations-pr=1275 --variations-override-country=ca

Quick Note: we're using --variations-override-country=ca due to griffin.brave.com not supporting x-country header

• restarted 1.74.48 Chromium: 132.0.6834.83
• ensured pull/1275@783ce3e2f737f54091ef23b0f4abc7e33b6418f1 via brave://version
• ensured that BraveSearchPromotionButtonStudy is NOT appearing/being used under brave://version
• change the default SE from Brave -> DDG via brave://settings/search
• ensure that the Brave promotional banner is NOT being displayed/used

`Example	Example	Example	Example

[kjozwiak]

Uplift into main/production approved 👍 QA has verified that the Griffin study is working as expected on Nightly, BETA & Release as per #1275 (comment). QA also verified the feature as per brave/brave-browser#40776.